Rankers Physics
Topic: Capacitors
Subtopic: Combination of Capacitors

Three capacitors 2 μF, 3 μF and 5 μF can withstand voltages to 3V, 2V and 1V respectively. Their series combination can withstand a maximum voltage equal to
5 Volts
(31/6) Volts
(26/5) Volts
None

Solution:

Let's verify and calculate the correct answer step-by-step:

Given Data:

  • Capacitances:
    C1=2μF,C2=3μF,C3=5μFC_1 = 2 \, \mu\text{F}, C_2 = 3 \, \mu\text{F}, C_3 = 5 \, \mu\text{F}
     
  • Maximum voltages:
    V1=3V,V2=2V,V3=1VV_1 = 3 \, \text{V}, V_2 = 2 \, \text{V}, V_3 = 1 \, \text{V}
     

Step 1: Maximum charge each capacitor can store:

 

Q1=C1V1=23=6μCQ_1 = C_1 \cdot V_1 = 2 \cdot 3 = 6 \, \mu\text{C}

 

Q2=C2V2=32=6μCQ_2 = C_2 \cdot V_2 = 3 \cdot 2 = 6 \, \mu\text{C}

 

Q3=C3V3=51=5μCQ_3 = C_3 \cdot V_3 = 5 \cdot 1 = 5 \, \mu\text{C}

 

The capacitor with the minimum charge capacity limits the system. Here,

Qmax=5μCQ_{\text{max}} = 5 \, \mu\text{C}

, dictated by

C3C_3

.


Step 2: Voltage distribution across each capacitor:

In series, charge

QQ

is the same on all capacitors, and the voltage across each capacitor is:

 

V1=QC1,V2=QC2,V3=QC3V_1 = \frac{Q}{C_1}, \quad V_2 = \frac{Q}{C_2}, \quad V_3 = \frac{Q}{C_3}

 

Total voltage across the series combination:

 

Vtotal=V1+V2+V3V_{\text{total}} = V_1 + V_2 + V_3

 

Substitute

Q=5μCQ = 5 \, \mu\text{C}

:

 

V1=52=2.5V,V2=531.67V,V3=55=1VV_1 = \frac{5}{2} = 2.5 \, \text{V}, \quad V_2 = \frac{5}{3} \approx 1.67 \, \text{V}, \quad V_3 = \frac{5}{5} = 1 \, \text{V}

 


Step 3: Total voltage:

 

Vtotal=V1+V2+V3=2.5+1.67+1=156+106+66=316V.V_{\text{total}} = V_1 + V_2 + V_3 = 2.5 + 1.67 + 1 = \frac{15}{6} + \frac{10}{6} + \frac{6}{6} = \frac{31}{6} \, \text{V}.

 


Final Answer:

The maximum voltage the series combination can withstand is:

 

316V5.17V.\boxed{\frac{31}{6} \, \text{V}} \approx 5.17 \, \text{V}.

 

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